With the development of telecommunication networks, an optical network has become a core of the future Wide Area Network (WAN) and Metropolitan Area Network (MAN). A Wavelength Division Multiplexing (WDM) optical network is of widespread concern, and with the emergence of an Optical Wavelength Routing Switch (WRS) and a Photonic Cross-Connector (PXC), data exchange may be implemented in an optical domain in the network.
In the WDM optical network, an optical channel needs to be determined by optical switching nodes, an optical link (optical fiber), and a wavelength (channel) assigned to each optical link. In an all-optical group that does not have a wavelength conversion capability, the optical channel must be established by using a common wavelength of all links along a route, which is a wavelength continuity restriction. During optical channel calculation, routing and wavelength assignment must be considered at the same time. That is because even though the route exists, in which each link of the route has a wavelength resource, if no common wavelength of all the links exists, the optical channel may not be established.
To relax the wavelength continuity restriction, an optical cross-connection device with the wavelength conversion capability may be deployed in the network, so that the optical channel is divided into several sub-connections of different wavelengths to form an optical path. However, due to constraint of factors such as technologies and costs, the device does not have arbitrary port cross-connection and arbitrary wavelength conversion capability, which therefore increases the difficulty of calculating wavelength routing.
With the development of service requirements and optical network technologies, the evolution from an optical transfer network to an intelligent optical network is an inexorable trend of the optical network development. An Automatic Switched Optical Network (ASON) is a new generation optical network integrating switching and transferring, which is a dynamic, automatic switched transfer network and is capable of automatically calculating a path and implementing establishment, restoration, and removal of a connection through signaling control. Therefore, the ASON and the WDM are combined, and the wavelength routing in the WDM optical network may be automatically calculated and established through the ASON, which is a new optical transfer mode.
However, due to the wavelength continuity restriction in the WDM optical network and a cross-connection restriction of the optical cross-connection device, a wavelength division device may not cross-connect an arbitrary wavelength channel to another wavelength channel, which makes it difficult for the ASON to calculate the path in the WDM optical network. In the prior art, the following method is provided to solve the cross-connection restriction problem of a WDM optical network device. Routing and wavelength assignment are performed separately. A route is selected without considering the wavelength resource, and then a signaling is sent along the route for detecting to determine available wavelengths. If it is detected that no wavelength resource along the selected route is available, a signaling crank-back is performed and other routes are reselected for redetection.
The disadvantage of this method is as follows. Channel establishment efficiency is low, so that the time of connection establishment or rerouting is too long, and the method may not take full advantage of network resources to maximize wavelength utilization efficiency.